1. Field of the Invention
The present invention relates to a printer, and more specifically to an image forming apparatus including a circulating transfer path having a sheet reversing mechanism.
2. Description of the Related Art
There has been known a double-sided printer which has a circulating transfer path including a sheet reversing mechanism and which reverses a sheet printed on one side to perform printing on the other side. There has recently been an increasing demand that a printer should have an improved productivity with faster printing speed. To achieve this, the printer is required to perform not only single-side printing but also double-side printing at a high productivity with faster printing speed.
The productivity of the printer depends mostly on a speed of image formation by a printing mechanism and a speed of transferring a print sheet by a transfer mechanism. Japanese Patent Application Publication No. 2005-280897 describes that productivity is improved by controlling, during double-side printing, a sheet transfer speed in circulating transfer according to a sheet size, independently of a sheet transfer speed in printing.